Motor vehicles are equipped with a windshield wiper device for cleaning or wiping a surface of a windshield. The windshield wiper device includes a wiper motor, a wiper arm and a wiper blade. The wiper arm is connected to a rotating shaft of the wiper motor at its base end and is oscillated by the wiper motor. The wiper blade is separably joined to a distal end of the wiper arm. The wiper blade is positioned on the surface of the windshield by the wiper arm. The wiper blade wipes the surface of the windshield while sliding thereon through oscillating movements of the wiper arm.
The wiper blade has an elongated wiper strip and a frame for holding and supporting the wiper strip in its longitudinal direction. The wiper strip is placed in contact with the windshield surface. The frame may comprise an assembly including a main yoke and a plurality of sub yokes linked to the main yoke. A wiper blade with such a frame is known in the art as “a conventional wiper blade.” A wiper blade, which uses a single frame curving with a certain curvature and having a thin and elongated bar shape as the frame, has been recently used. Such a wiper blade is known in the art as “a flat wiper blade” or “a flat-bar wiper blade.” The flat wiper blade has a height lower than a conventional wiper blade and is subjected to less air resistance when compared to the conventional wiper blade. Further, the flat wiper blade can bring its wiper strip into contact the windshield surface under a uniform load.
The flat wiper blade may be connected to a wiper arm via a connecting unit attached to a midway section of a frame and is separably coupled to a distal end of the wiper arm. FIG. 1 shows “a hook wiper arm” with a hook-shaped distal end portion as one example of the wiper arm. The hook wiper arm 1 has been widely used due to a simple shape of the distal end portion. The flat wiper blade and the hook wiper arm 1 are connected to each other by using such a hook shape. By way of example, Korean Patent Application Publication No. 10-2005-0033046 discloses a connection example between a flat wiper blade and a hook wiper arm. This reference teaches that the flat wiper blade and the hook wiper arm are connected to each other in such a manner that a connecting unit attached in the flat wiper blade is hooked to a hook portion of the hook wiper arm.